Generic powerpc branch analysis support added in the code patching
library which will help the subsequent patch on SW based filtering
of branch records in perf.
Signed-off-by: Anshuman Khandual <khand...@linux.vnet.ibm.com>
---
arch/powerpc/include/asm/code-patching.h | 16 +++++++
arch/powerpc/lib/code-patching.c | 80 ++++++++++++++++++++++++++++++++
2 files changed, 96 insertions(+)
diff --git a/arch/powerpc/include/asm/code-patching.h
b/arch/powerpc/include/asm/code-patching.h
index 97e02f9..39919d4 100644
--- a/arch/powerpc/include/asm/code-patching.h
+++ b/arch/powerpc/include/asm/code-patching.h
@@ -22,6 +22,16 @@
#define BRANCH_SET_LINK 0x1
#define BRANCH_ABSOLUTE 0x2
+#define XL_FORM_LR 0x4C000020
+#define XL_FORM_CTR 0x4C000420
+#define XL_FORM_TAR 0x4C000460
+
+#define BO_ALWAYS 0x02800000
+#define BO_CTR 0x02000000
+#define BO_CRBI_OFF 0x00800000
+#define BO_CRBI_ON 0x01800000
+#define BO_CRBI_HINT 0x00400000
+
unsigned int create_branch(const unsigned int *addr,
unsigned long target, int flags);
unsigned int create_cond_branch(const unsigned int *addr,
@@ -56,4 +66,10 @@ static inline unsigned long ppc_function_entry(void *func)
#endif
}
+/* Perf branch filters */
+bool instr_is_return_branch(unsigned int instr);
+bool instr_is_conditional_branch(unsigned int instr);
+bool instr_is_func_call(unsigned int instr);
+bool instr_is_indirect_func_call(unsigned int instr);
+
#endif /* _ASM_POWERPC_CODE_PATCHING_H */
diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c
index d5edbeb..a06f8b3 100644
--- a/arch/powerpc/lib/code-patching.c
+++ b/arch/powerpc/lib/code-patching.c
@@ -77,6 +77,7 @@ static unsigned int branch_opcode(unsigned int instr)
return (instr >> 26) & 0x3F;
}
+/* Forms of branch instruction */
static int instr_is_branch_iform(unsigned int instr)
{
return branch_opcode(instr) == 18;
@@ -87,6 +88,85 @@ static int instr_is_branch_bform(unsigned int instr)
return branch_opcode(instr) == 16;
}
+static int instr_is_branch_xlform(unsigned int instr)
+{
+ return branch_opcode(instr) == 19;
+}
+
+/* Classification of XL-form instruction */
+static int is_xlform_lr(unsigned int instr)
+{
+ return (instr & XL_FORM_LR) == XL_FORM_LR;
+}
+
+/* BO field analysis (B-form or XL-form) */
+static int is_bo_always(unsigned int instr)
+{
+ return (instr & BO_ALWAYS) == BO_ALWAYS;
+}
+
+/* Link bit is set */
+static int is_branch_link_set(unsigned int instr)
+{
+ return (instr & BRANCH_SET_LINK) == BRANCH_SET_LINK;
+}
+
+/*
+ * Generic software implemented branch filters used
+ * by perf branch stack sampling when PMU does not
+ * process them for some reason.
+ */
+
+/* PERF_SAMPLE_BRANCH_ANY_RETURN */
+bool instr_is_return_branch(unsigned int instr)
+{
+ /*
+ * Conditional and unconditional branch to LR register
+ * without seting the link register.
+ */
+ if (is_xlform_lr(instr) && !is_branch_link_set(instr))
+ return true;
+
+ return false;
+}
+
+/* PERF_SAMPLE_BRANCH_COND */
+bool instr_is_conditional_branch(unsigned int instr)
+{
+ /* I-form instruction - excluded */
+ if (instr_is_branch_iform(instr))
+ return false;
+
+ /* B-form or XL-form instruction */
+ if (instr_is_branch_bform(instr) || instr_is_branch_xlform(instr)) {
+
+ /* Not branch always */
+ if (!is_bo_always(instr))
+ return true;
+ }
+ return false;
+}
+
+/* PERF_SAMPLE_BRANCH_ANY_CALL */
+bool instr_is_func_call(unsigned int instr)
+{
+ /* LR should be set */
+ if (is_branch_link_set(instr))
+ return true;
+
+ return false;
+}
+
+/* PERF_SAMPLE_BRANCH_IND_CALL */
+bool instr_is_indirect_func_call(unsigned int instr)
+{
+ /* XL-form instruction with LR set */
+ if (instr_is_branch_xlform(instr) && is_branch_link_set(instr))
+ return true;
+
+ return false;
+}
+
int instr_is_relative_branch(unsigned int instr)
{
if (instr & BRANCH_ABSOLUTE)
--
1.7.11.7
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